Just about to give up on this car

[87moostang]

Ok, 1987 Mustang 306 Ford crate motor. Ran good at initial startup when I dropped motor, engine would start easily and idle, but occasionally while driving and letting off gas pedal and slowing down it would get an erratic idle and stall. The problem kept getting progressivley worse to the point now it wouldnt even idle. The fuel pump ,IAC is new, coil, dizzy, cool temp sensor, act sensor, plug wires all new from install of new motor. It did start some weird "glitching" of the tach the last time I started it which is really odd because I have never seen it do this. Almost like an electrical problem yet the problem sounds and feels like a bad IAC. I am pretty sure my Moostang is cursed so if anyone knows a Catholic Priest willing to exorcise this car please let me know. I have spent all the mooolah I m gonna spend on this turd because it is my 2nd engine since January , long story there.Oh yeah just for fun I had another IAC that is known to be good, yet it didnt change the way the car was running.
Thanks for any help

[JIMS SVT]

Vac leak possibly?

[Dirtyd0g]

What did you do with the rocker arms are they stock or aftermarket? If they are aftermarket are they adjustable?
Alan

[Racin Jason]

Check ur pc ground. Is it mass air converted? Hit me up if u want. Maybe we can hook up and figure it out

[blown96cobra]

Check under the steering column for a loose wire at the ignition switch.